The present invention relates to an intermediate transfer recording medium which is used to form an image on a transfer-receiving member and a protective layer on the image to thereby impart durability to the image and which can simply transfer the protective layer to the image with accuracy. The present invention also relates to an image forming method.
Conventionally, various thermal transfer methods have been known in which, a thermal transfer sheet formed with a color transfer layer on a substrate sheet is heated imagewise from the backface thereof by using a thermal head to thermally transfer the above color transfer layer to the surface of a thermal transfer image-receiving sheet thereby forming an image.
These thermal transfer methods are loosely classified into two systems, namely, a sublimation transfer type and a heat melting transfer type depending upon the structure of the color transfer layer. The two systems enable the formation of a full-color image. For instance, thermal transfer sheets with three colors of yellow, magenta and cyan or with four colors including a black color as required in addition to the above three colors are prepared and each color image is overlapped on and thermally transferred to the same thermal transfer image-receiving sheet to form a full-color image.
With the progresses of various hardware and software applications in relation to multimedia, markets for the thermal transfer method have been broaden in the fields of full-color hard copy systems used for computer graphics, static images sent by satellite communications, digital images represented by those of CD ROMs and the like and analog images of videos and the like.
Specific applications of the thermal transfer image-receiving sheet used in this thermal transfer method are diversified. Typical examples of the application include proof of printing, outputs of images, outputs of layout and design in CAD/CAM, output applications for various medical analysis or measuring instruments, e.g., CT scans and endscope cameras, substitutions for instant photographs, outputs of photographs of a face and the like in papers of identification, ID cards, credit cards and other cards, combination photographs and commemorative photographs handled in amusement facilities, e.g., amusement parks, game centers, museums and aquariums.
Along with the diversification of applications as aforementioned, there has been an increased demand for forming a thermal transfer image on an optional subject. As one of measures devised to deal with the demand, a method is proposed in which using an intermediate transfer recording medium provided peelably with a receptor layer on a substrate wherein a thermal transfer sheet having a dye layer is used as the receptor layer, a dye is transferred to form an image and thereafter the intermediate transfer recording medium is heated to transfer the receptor layer to a transfer-receiving member (see Japanese Patent Application Laid-Open No. 62-238791).
When a sublimation transfer-type thermal transfer sheet is used to form an image, gradational images such as photographs of a face can be formed precisely. However, this method has weak points that, unlike an image formed by usual printing ink, the formed image lacks in durability regarding, for example, weatherability, friction resistance and chemical resistance.
To solve the problem, a protective layer thermal transfer film having a thermal transfer resin layer is overlapped on a thermal transfer image and the thermal transfer resin layer having transparency is transferred using a thermal head or heating roll to form a protective layer on the image.
The above protective layer must have layer-cuttability because it must be transferred in part when it is transferred using a thermal head or a heating roll. In this case, it is inevitable that the protective layer is formed of a resin film with a thickness of about several microns and it is hence impossible to make the protective layer possess durability regarding, for example, strong resistance to abrasion and chemical resistance.
Also, a protective layer to be formed on an intermediate transfer recording medium is not made to have durability regarding, for example, strong resistance to abrasion and chemical resistance in view of the necessity of layer cuttability.
There will be a method in which an image is formed on a transfer-receiving member by using an intermediate transfer recording medium and a resin film is laminated so as to cover the image on the transfer-receiving member to form a protective layer. However, it is considered that wrinkles are formed on the resin film when laminatig, depending upon the shape of the transfer-receiving member and it is hence necessary to treat these wrinkles using a special machine such as a laminator, leading to increased steps.